Effects of microcrystalline plant sterol suspension and a powdered plant sterol supplement on hypercholesterolemia in genetically obese Zucker rats

Pharmacokinetic comparison of a generic coenzyme Q₁₀ solubilizate and a formulation with soybean phytosterols

Coenzyme Q₁₀ (CoQ₁₀) is essential for all cells, and deficiency has been implicated in cardiovascular disease. Plant phytosterols inhibit cholesterol absorption, and may thereby also reduce cardiovascular risk. This study compared the relative bioavailability of CoQ₁₀ solubilized in low-dose soybean phytosterols (SterolQ₁₀) with a generic CoQ₁₀ solubilizate. In a randomized, cross-over design, 36 healthy males received a single 100 mg dose of CoQ₁₀, as SterolQ₁₀ or generic CoQ₁₀, with a two-week washout between treatments. Plasma CoQ₁₀ was analysed at baseline, and at 2, 4, 6, 8 and 10 h after supplement ingestion. Subjects were then administered either 100 mg/day of generic CoQ₁₀ or SterolQ₁₀ for 4 weeks. Fasting plasma CoQ₁₀ levels were measured at baseline and following supplementation. The two preparations were bioequivalent in regard to the area under the curve (AUC(0-10h) ) and maximum increase in concentration (C(max) ), with geometric mean ratios of 0.89 (CI 0.81-0.98) and 0.88 (CI 0.80-0.96), respectively. Four-weeks of CoQ₁₀ resulted in a comparable twofold increase in CoQ₁₀ levels for both formulations (p < 0.001), which was similar between preparations (p = 0.74). The combined CoQ₁₀ and phytosterol formulation, SterolQ₁₀, showed bioequivalence to the generic CoQ₁₀ following a single CoQ₁₀ dose, and demonstrated comparable bioavailability following multiple dose administration.

Effect of phytosterols on copper lipid peroxidation of human low-density lipoproteins

OBJECTIVE

Phytosterols and stanols have received much attention in the past several years because of their cholesterol-lowering properties, and several studies have shown a protective effect against cardiovascular disease and colon and breast cancer development. A significant decrease of plasma low-density lipoprotein (LDL) cholesterol and apolipoprotein B has been demonstrated in subjects whose diet was supplemented with 2g/d of plant sterols. Changes in plasma lipoprotein levels were associated with a decrease of oxidized LDL, suggesting that plant sterols could exert an antioxidant effect. The aim of the present study was to further investigate the interaction between the major dietary phytosterols and plasma lipoproteins. Moreover, their antioxidant effect against in vitro-induced lipid peroxidation of human LDL was investigated.

METHODS

Susceptibility to copper-induced lipid peroxidation was investigated in LDLs isolated from plasma of normolipemic subjects. Concentrations of beta-sitosterol, campesterol, and stigmasterol ranging from 5 to 50 microM were studied. Analyses of the emission fluorescence spectra of tryptophan and of the probe 6-dodecanoyl-2-dimethyl-aminoaphthalene were used to investigate the effect of phytosterols on apoprotein structure and physicochemical properties of LDL.

RESULTS

Our results demonstrated that phytosterols exert an inhibitory effect against copper-induced lipid peroxidation of LDLs, as shown by the lowered levels of conjugated dienes in oxidized lipoproteins incubated with different concentrations of plant sterols (5-50 microM). Moreover, analysis of fluorescence emission spectra of tryptophan and 6-dodecanoyl-2-dimethyl-aminoaphthalene demonstrated that phytosterols prevent the alterations of apoprotein structure and physicochemical properties associated with copper-triggered lipid peroxidation of lipoproteins.

CONCLUSION

We suggest that the effect exerted by beta-sitosterol, stigmasterol, and campesterol against lipid peroxidation of LDL possibly related to phytosterol-lipoprotein interactions could be of physiologic relevance.